Freshwater Demand Research Articles

Designing a Single Slope Solar Water Still and Testing it in Omani Climate

Oman has a limited resources of fresh water mainly underground water. To preserve those resources and to meet the increase in the fresh water demand, the country turned to water desalination which is known to be very costly and harmful to the environment. Water desalination using solar energy is an attractive alternative for countries like Oman which has a sunny weather all year round and where the length of the day time ranges between 11 to 14 hours. Furthermore, solar energy is a clean source of energy. The aim of the present study is to (1) design and test the solar water still for Omani climate, and (2) to investigate the effect of different design parameters on the still thermal performance.

Sunwater and beyond

Due to the increasing water shortages not only in sunny countries, but also in a lot of other states, the demand on freshwater will increase worldwide in the near future. Good examples are the newly industrializing countries. The freshwater demand increases with the wealth of the inhabitants. The so called virtual water must also be taken into account. This is water which is needed to produce products, but it is not included in the final commodity. During the Sunwater project a demonstration plant was planned, modeled, simulated and installed which uses renewable energies to desalinate freshwater with a very high quality. Solar thermal energy was used to convert saltwater from the Red Sea into freshwater. For this purpose an innovative evaporation desalination unit from Germany was used. The complete project was a feasibility study with partners from Germany, Egypt and UK. In this paper a few modifications and additional application possibilities are presented to use this demonstration plant. This includes e. g. other prospects for the heat storage tanks and the usage of the water desalination unit itself.

In-reservoir transformation of dissolved organic matter as a function of hydrological flow

Reservoirs are vital to meet the ever-increasing demands for freshwater in a warming climate. Dissolved organic matter (DOM) represents an important pool of carbon and can be a major concern in drinking water sources. However, insights into DOM dynamics in temperate, semi-arid reservoirs remain limited. Therefore, we investigated the variations in DOM properties in Lake Diefenbaker, a large reservoir on the Canadian Prairies, by analyzing eight years of DOM concentrations and composition through linear mixed effect modeling. Contrary to expectations, reservoir dissolved organic carbon (DOC) concentration showed no correlation with inflow from the South Saskatchewan River (p = 0.12), while dissolved organic nitrogen (DON) increased with decreasing inflow (p = 0.002). DOM optical indices (SUVA254 and E4:E6 ratio) and DOC:DON ratio revealed a pronounced influence of inflow on reservoir DOM composition (p < 0.001), i.e., allochthonous characteristics increased with increasing flow, and autochthonous characteristics increased with declining flow. Travel time corrected comparison of approximately the same water parcel along the reservoir length revealed that increasing water residence time in downstream regions led to a significant transformation in DOM composition, favoring autochthonous characteristics (mean SUVA254 reduced by 0.52 L mg-C−1 m−1, and the E4:E6 and spectral slope ratio increased by 1.6 and 0.06, respectively). Autochthonous DOC inputs likely offset the allochthonous DOC losses, which resulted in a relatively stable DOC concentration throughout the reservoir (mean 3.7 mg L−1). Additionally, the effect of a large aquaculture operation on reservoir DOM properties was investigated, but no effect was detected. The results have significant implications for managing large river-reservoirs. Autochthonous DOM poses challenges to water processing, necessitating monitoring of DOM composition for reservoir drinking water quality. Insights on climate-induced changes in DOM properties will also assist with understanding changes to habitat conditions and contaminant transport.

Internet of things sensors and support vector machine integrated intelligent irrigation system for agriculture industry

Because there is more demand for freshwater around the world and the world’s population is growing at the same time, there is a severe lack of freshwater resources in the central part of the planet. The world’s current population of 7.2 billion people is expected to grow to over 9 billion by the year 2050. The vast majority of freshwater is used for things like cooking, cleaning, and farming. Most industrialised countries are in desperate need of smart irrigation systems, which are now a must-have because of how quickly technology is improving. In article presents IoT based Sensor integrated intelligent irrigation system for agriculture industry. IoT based humidity and soil sensors are used to collect soil related data. This data is stored in a centralized cloud. Features are selected by CFS algorithm. This will help in discarding irrelevant data. Clustering of data is performed by K means algorithm. This will help in keeping similar data together. Then classification model is build using the SVM, Random Forest and Naïve Bayes algorithm. Model is trained, validated and tested using the acquired data. Historical soil and humidity related data is also used in training the model. K-means SVM hybrid classifier is achieving better results for classification, prediction of water demand and saving fresh water by intelligent irrigation. K-means SVM hybrid classifier has achieved accuracy rate of 98.5 percent. Specificity, recall and precision of K-means SVM hybrid classifier is also higher than random forest and naïve bayes classifier.

Spicing up membrane distillation: Enhancing PVDF membrane performance with cinnamic acid

The increasing demand for freshwater is driving the rapid development of new water treatment materials. Furthermore, there is significant pressure to replace the toxic substances often used in membrane production with environmentally friendly, biocompatible, and natural compounds. In this work, poly(vinylidene fluoride) (PVDF) membranes were modified for the first time with a naturally occurring, non-toxic, biodegradable substance – cinnamic acid. The application of its molecules for membrane modification allows for diminishing the problem of bioaccumulation and toxicity in the environment. The procedure was selected with the accordance of green chemistry principles (green modifier – cinnamic acid, and green solvent – ethanol), and employed to chemically bind the modifier to the membrane surface. The modified membranes exhibited an increase in the hydrophobicity of the surface. The water contact angle increased from 124.7° for the pristine membrane to 139.3° for the membrane modified with a 10 % concentrated solution of cinnamic acid (PVDF-Cin10). All membranes possessed an excellent salt rejection coefficient. Membrane antiwetting features have been determined under challenging conditions of salt (3 M NaCl) and low surface tension liquid (sodium dodecyl sulfate). The dynamic goniometric studies were implemented to evolve membranes' wetting stability.

Ice templated and ice seed tailored hydrogels for highly efficient solar evaporator

In recent years, freshwater resources have become a global concern, and solar vapor generation (SVG) has garnered significant attention from researchers. Herein, a novel hydrogel solar evaporator was prepared by incorporating lignin and CuS-rGO into a chitosan-gelatin matrix. The anisotropic and isotropic morphologies of the hydrogel were prepared by pathway control on the solidification velocities of ice crystals and ice seeds. It presented that the anisotropic morphology can improve the refraction of light and increase the utilization rate of light by forming a light trap, leading to higher water evaporation rate. Additionally, ice seed was introduced during the freezing process, producing an anisotropic hydrogel with curled layer structure that endowed lower enthalpy of water evaporation and faster water transfer rate, resulting in high evaporate of 3.62 kg m−2 h−1 under one solar irradiation with photothermal conversion efficiency of 97.7 %. Finally, the gel also demonstrated good mechanical properties, long-term working stability and harsh environment tolerance, which make it ideal for outdoor applications. The hydrogel evaporator had potential to generate 25.24 kg m2 water per day that could meet the huge demand for freshwater as sources.

Improving solar still productivity via fin optimization: computational and experimental investigations

ABSTRACT Solar desalination offers a promising solution to conserve energy and meet the growing demand for freshwater. To improve the productivity of solar stills, the incorporation of fins on the absorber has been explored. This study aims at investigating the impact of various fin geometric parameters on solar still efficiency using an experimentally validated Computational Fluid Dynamics (CFD) model. The study specifically examines the height, width, and spacing between the fins, with three levels assessed for each parameter. Solar radiation and temperature distributions are measured through an experimental design. The discrete ordinate (DO) model is used to capture the solar radiation, while the k-ε Renormalization-group (RNG) is employed to investigate the effect of the turbulence. To ensure mesh independent results, a grid size independence test is conducted. The CFD results are validated against experiments, demonstrating an error less than 4%. The findings show that fins having a height of 30–50 mm increase basin temperature by 2.6%, boosting freshwater productivity by 0.03 l/m2.h, and improving solar still efficiency by 1.74%. Widening fin width raises water basin temperature by 10.4%, resulting in 4% efficiency enhancement. Reducing fin spacing from 130 mm to 30 mm increases productivity by 0.04 l/m2.h, which corresponds to 2.48% efficiency improvement. These findings suggest a careful consideration of fin design parameters can further enhance this efficiency.

Development of concentrated solar and agrivoltaic based system to generate water, food and energy with hydrogen for sustainable agriculture

Water, food and energy together form a critical nexus which is at the core of sustainable development. Agricultural activities are the major consumers of water and energy, while on the other hand, energy generation is another major reason for water consumption. With the growing population and economies, there is an increasing pressure on water, food and energy nexus and their management. Therefore, it is a necessity to develop dual, triple, or multiple benefits from single systems or applications in order to maximize the effective and efficient utilization of sources. It is also necessary to multiply the benefits of the land; agrivoltaics maximize the benefit of the land by combining solar photovoltaics and food crops on the same land. Moreover, the process heat is an important useful commodity to multiply the benefits of the integrated energy systems. The concentrated solar power (CSP) systems can generate process heat for many applications, and we propose to use such systems on agricultural lands and to call this as “agri-CSP”. Moreover, different agrivoltaic orientations are comparatively assessed with newly suggested agri-CSP. The agrivoltaic and concentrated solar energy systems generate power and process heat in order to meet electricity, fresh water, space heating, space cooling and hydrogen demands of a farm community. The first and second laws of thermodynamics are considered while designing and analyzing the integrated system. Realistic simulations are carried out with software packages where commercially available products and actual meteorological data are considered. The study results show that a community of 86,000 people with farms in California can be self-sufficient with the proposed system. The agri-CSP is designed to orient accordingly and generates 1716 MWh of electricity per MWp capacity in a typical year, where a MWp of agrivoltaic generates 1338.7 MWh of electricity with vertical-fixed orientation, 2040.5 MWh of electricity with tilted-fixed orientation, 2365.7 MWh of electricity with tracking orientation. Moreover, 959.06 k-tonnes of fresh water and 290.07 t of hydrogen are additionally generated. The overall energy and exergy efficiencies of the proposed integrated system are obtained as 59.95% and 41.01% on average in a typical year.

Machine learning assisted water management strategy on a self-sustaining seawater desalination and vegetable cultivation platform

To enable vegetable cultivation in conditions lacking freshwater and soil, such as islands and offshore platforms, this study proposes to combine interfacial solar evaporation with hydroponic techniques to set up an electricity-free self-sustaining desalination and cultivation platform. To maintain a dynamic balance between freshwater supply and demand on the platform, we investigate the relationship between water consumption in hydroponic lettuce cultivation and meteorological conditions such as temperature, humidity, and solar radiation. The limitations of traditional evapotranspiration models like the FAO-PM model in practical hydroponic cultivation is highlighted and four machine learning algorithms, including Random Forest, Backpropagation Neural Network, Support Vector Regression, and N-BEATS, are developed to predict water consumption specifically for hydroponic cultivation. The Random Forest model, selected based on performance comparison, achieves MAPE and R2 values of 10.05% and 0.974 respectively on the test set. Using meteorological data from Shanghai in 2022, the feasibility of the platform is assessed, demonstrating a theoretical lettuce yield of 260 plants/m2/year for solar stills on a unit area without water shortages throughout the year. This study verifies the feasibility and stability of the hydroponic cultivation platform, and is promising for the development of sustainable agriculture in offshore scenarios with limited freshwater and soil resources.

Super-hydrophilic LaCoO3/g-C3N4 nanocomposite coated beauty sponge for solar-driven seawater desalination with simultaneous volatile organic compound removal.

Interfacial solar steam generation (ISSG) is emerging as a promising, environment-friendly solution for fulfilling freshwater and energy demands. However, a critical challenge for ISSG lies in the presence of harmful volatile organic compounds (VOCs) in the feedwater which are co-evaporated with water, leading to more enriched concentration in condensed water. Herein, lanthanum cobaltate-graphitic carbon nitride (LaCoO3/g-C3N4, LCO/g-CN) nanocomposite decorated beauty sponge (LCO/g-CN@BS) is proposed as an efficient photothermal/photocatalytic material for solar-driven seawater desalination and simultaneous VOC degradation. The hydrophobic surface of the beauty sponge after LCO/g-CN coating becomes super-hydrophilic, ensuring sufficient water supply and our LCO/g-CN@BS delivers an evaporation rate of 1.94 kg m-2 h-1 under 1 sun irradiation. This LCO/g-CN@BS shows excellent seawater desalination capacity with a self-cleaning ability when employed for saltwater purification for a salt (NaCl) concentration as high as 15 wt%. Moreover, fast photocarrier transfer between LCO and g-CN leads to enhanced photocatalytic degradation of over 90% of phenol simultaneously, which is about 60% for only an LCO-based beauty sponge. This work presents a promising approach to combining novel nanocomposites with microporous structures for efficient solar desalination, offering simultaneous VOC degradation.

Assessment of Municipal and Industrial Wastewater Impact on Yamuna River Water Quality in Delhi

Delhi's Yamuna River serves as a notable illustration of an ecologically compromised system that has undergone a transition into a conduit for sewage due to pervasive pollution and escalating anthropogenic influences. Delhi, being the primary contributor to pollution, is responsible for over 70% of the total pollutant load in the Yamuna. The city's drainage systems discharge a substantial Biological Oxygen Demand load into the river daily, resulting in severe pollution. This research utilizes pre-existing data to examine diverse factors, evaluating the quality of water at distinct observation locations along the Yamuna. The utilization of correlation analysis aids in recognizing connections among elements influencing the pollution of river water. The outcomes of the correlation analysis disclose a notable link between COD-BOD factors, whereas the connections among alternative factors like BOD-DO, BOD-pH, COD-DO, COD-pH, and DOpH range from moderate to negligible. The majority of observed parameters exceed hazardous levels deemed acceptable for river water utilization. The evaluation of Sewage Treatment Plants highlights the imperative to augment capacity in terms of treatment, storage, reactivation of closed plants, and efficient operation to meet the growing demand for fresh water. Additionally, there is a pressing need to generate demand for wastewater in diverse urban sectors.

Thermo-Economic Analysis of Gas Turbine Combined Multistage Flash (MSF) Desalination Cycle

Over the past few decades, the growth of the earth’s population has increasingly contributed to global warming, and increased demand for fresh water on top of a need for a greater power supply. This paper will analyze the integration of a combined- gas turbine with intercooler and a multi-stage flash (MSF) desalination plant for the simultaneous generation of electricity and supply of water and improved performance. The paper will also examine the calculation of the production cost and the capital cost of the MSF desalination plant. The thermo-economic analysis of the study was conducted using the IPSEpro software system. Also, exergy losses of the gas turbine and MSF desalination unit were also calculated. The desalination plant uses the exhaust gases from the gas turbine, as a form of thermal energy, and discharges to feed the seawater heater. A portion of the desalinated water is used to cool the compressed air in the intercooler heat exchanger. Results indicate the improvement in the gas turbine’s performance when desalinated water is used for the intercooler between compressor stages, as the power output increased by 59% over the the simple gas cycle and found decrease with an increase in the ambient temperature. The desalinated water cost was calculated to be $1.7 per cubic meter after determining the optimal configuration and operating conditions. A decrease in steam cost by 36% was observed when the waste heat from the gas turbine was used as the source of thermal energy. Part of this reduction can be explained by the observation that the desalination plant’s pumps consume part of the power generated by the gas turbine.

Comparative study of the quality of water produced by a solar distiller and by reverse osmosis

Freshwater is a vital resource for human well-being, accounting for about 2.5% of the water on our planet. However, the growing demand for freshwater puts its quality at risk. For meeting the water needs, desalination is a crucial solution, but it needs to be ensured that the water quality meets the international standards. In this article, we will compare the physical and chemical characteristics of water produced by solar distillation and reverse osmosis, using the same source water. We started with saline water with a pH ranging from 7.70 to 7.80, conductivity ranging from 49.5 to 51 ms/cm, and bicarbonate ion concentration ranging from 125 to 145 mg/l. We used a solar distiller and reverse osmosis to obtain distilled water with a pH of 7 to 7.20, conductivity of 0.2 to 1.6 ms/cm, and bicarbonate ion concentration of 14 to 28.5 mg/l. The results we obtained were found to comply with international drinking water standards.

Performance Study of the Al Hoceima Seawater Desalination Plant

The growing demand for freshwater, amplified by climate change, can lead to variations in precipitation patterns and cause more frequent and severe droughts, reinforcing the need for seawater desalination to meet these growing needs. Seawater desalination has become a vital solution in many countries, notably Morocco, which has launched an ambitious program to install seawater desalination plants using the reverse osmosis technique in semi-arid zones. The AL HOCEIMA seawater desalination plant came on stream in June 2020. To keep the plant running smoothly and assess the efficiency of all its operational processes, operating indicators for each treatment process were monitored and compared with expected performance. The results of the evaluation showed that the plant is performing well in terms of producing dimenarilated water by reverse osmosis, and this is due to the adequate pre- treatment adopted by the plant. However, optimizing the remineralization of desalinated water still poses a problem in terms of alkalinity and hardness. Treated water always has an aggressive, corrosive character.

A study on the influence of feed and draw solution concentrations on the performance of the pilot-scale forward osmosis-membrane distillation system

The increasing demand for freshwater and scarcity of natural sources of freshwater have led the world to turn to seawater as a main source to produce freshwater through conventional desalination processes. Multi-stage flash distillation (MSF) and reverse osmosis (RO) technologies are currently being utilized in the existing desalination plants. However, these technologies are energy-intensive and have their own limitations such as scaling and fouling. Therefore innovation in non-conventional desalination technologies has produced a number of promising systems including the newly developed integrated membrane system using forward osmosis (FO) and membrane distillation (MD). The scope of this study will assess the viability and efficiency of an FO-air gap MD (AGMD) integrated system of capacity 5 m3/day for desalination application using different concentrations of NaCl as feed and draw solutions. The FO-AGMD system performance was majorly evaluated in terms of water recovery. At a fixed DS concentration of NaCl at 70000 ppm, the highest water recoveries in the range of 50–60% were observed for the lowest FS concentration i.e. DI water attributed to the highest ∆Π difference across the FO membrane. The increased DS concentration at a fixed concentration of the FS decreased the average water recovery of the system attributed to the unique design of the FO-AGMD system. For the fixed NaCl concentration of FS at 5000 ppm, the FO-MD process with 35,000 ppm solution of NaCl as DS showed higher water recovery in the range of 46–51% compared to the DS concentration of 150,000 ppm NaCl, which showed water recovery in the range of 30–41% at the operating temperature of MD at 85 °C.

Combination of activated carbon/ultrafiltration as pre-treatment for seawater reverse osmosis plants

Seawater Reverse Osmosis (SWRO) is a common technology to treat seawater to comply high freshwater demand. Currently, the main issue of seawater/brackish water as the potential sources for drinking water is vulnerable to organic pollutants. An effective pre-treatment is crucial to maintain the efficiency of SWRO for sustainable operation. Optimization of the process could be performed by a hybrid membrane combination using commercial Activated Carbon (AC) with based material coconut shell/coal and Ultrafiltration membrane (UF). For hybrid process, the activated carbon was continuously dosed into the pilot scale filtration employing PES Hollow Fiber membrane with active area of 4 m² and average pore size of 10 nm that represents a real operation filtration process (i.e., filtration flux, filtration time, backwashing, and cleaning in place), and was performed until 8 filtration cycle sequence. This study investigated membrane performance with combination technique PAC/UF and GAC/UF in Pilot scale experiments within resistance membrane and retention membrane. Combination of Activated Carbon/Ultrafiltration showed synergistic effects in the removal of organic content for COD 40%-96%, UV-VIS 43%-92% and Turbidity 73%-99%. High removal of organics pollutants (COD, UV-VIS and Turbidity) was attributed to small average pore distribution of Activated Carbon (&lt;10 µm) that increase adsorption process. Moreover, hybrid Activated Carbon/UF adsorption kinetics can reduce filtration times to achieved optimal retention. Related to membrane performance, hybrid AC/UF resulted in less permeability declines almost double in first two filtration cycle and slightly less permeability decline until fifth cycle in comparison with single UF process. Better membrane performance can furtherly be explained from less irreversible fouling in case of AC/UF. Combination AC/UF enhanced the control of Irreversible fouling and resulted in better filtration performance as well as higher organic substance removal. Therefore, hybrid AC/UF could be seen as an effective system as pretreatment for SWRO.

Spatially distributed freshwater demand for electricity in Africa

Spatially distributed freshwater demand for electricity in Africa

Global Impact of Sea Level Rise on Coastal Fresh Groundwater Resources

AbstractGroundwater is the main freshwater source in many densely populated and industrialized coastal areas around the world. Growing future freshwater demand is likely to increase the water stress in these coastal areas, possibly leading to groundwater overexploitation and salinization. This situation will likely be aggravated by climate change and the associated projected sea level rise. Here, we assess the impact of sea level rise exclusively on coastal fresh groundwater resources worldwide (limited to areas with unconsolidated sedimentary systems) by estimating future decline in inland fresh groundwater volumes under three sea level rise scenarios following Representative Concentration Pathway (RCP) 2.6, 4.5, and 8.5. For that, 2D groundwater models in 1,200 coastal regions estimate the past, present and future groundwater salinity. Our results show that roughly 60 (range 16–96) million people living within 10 km from current coastline could lose more than 5% of their fresh groundwater resources by 2100 according to RCP 8.5 scenario compared to only 8 (range 0–50) million people based on RCP 2.6 scenario. We conclude that sea level rise will have severe consequences for many coastal populations heavily dependent on fresh groundwater.

Upstream water management and its role in estuary health, evaluation of freshwater management and subtropical estuary function

In highly modified and managed systems the balance of freshwater inputs discharged to estuarine systems are important to maintain salinity balances and thus estuarine function. However, the availability of freshwater is highly dependent on upstream water management to provide flood protection whilst meeting freshwater demand for people and the environment. In South Florida, water is managed by a water control plan with Lake Okeechobee at the center. Currently, water levels within the lake are managed based on the Lake Okeechobee Regulation Schedule of 2008. The new regulation schedule, Lake Okeechobee System Operating Manual (LOSOM), updates water management rules while attempting to balance the needs of downstream systems; salinity and water quality in the Caloosahatchee and Saint Lucie (northern) estuaries; and more water for the southern Everglades. This study evaluates LOSOM relative to ecologically significant performance measures for the northern estuaries. Overall, the proposed regulation schedule is expected to provide a more sustainable flow regime to the estuaries by reducing stressful and damaging discharge events. Moreover, new management rules combined with new infrastructure are expected to reduce low discharge events to the Caloosahatchee estuary and reduce stress on key indicator species such as Vallisneria americana during the wet season. This regulation schedule provides improved conditions for the estuaries at the expense of higher Lake Okeechobee stages. Future restoration and water management will maintain the benefits afforded to the estuaries while at the same time reducing the impacts to Lake Okeechobee resulting in a more sustainable and resilient system.

Insight into land cover dynamics and water challenges under anthropogenic and climatic changes in the eastern Nile Delta: Inference from remote sensing and GIS data

The destabilization of delta's worldwide due to climate change and human activities presents challenges in meeting the growing demands for freshwater and food. The Nile Delta in Egypt is a prime example of a vulnerable region facing various stressors. In order to preserve land and water resources, it is crucial to monitor the spatial and temporal changes in Land Use/Land Cover (LULC), shoreline, and Terrestrial Water Storage (TWS) in these vulnerable regions This study comprehensively investigates the dynamic changes in LULC and their associated water and soil responses in the Eastern Nile Delta under these combined impacts. To achieve this goal, a combination of remote sensing techniques utilizing Landsat (5, 8, and 9), and GRACE datasets, along with field observations and Geographic Information System (GIS) tools, was employed. Accordingly, shoreline changes show coastal erosion rates ranging from 5.28 to 34.92 m/year due to climate change-induced SLR, with continued inland movement predicted for the next 20 years. Moreover, the dynamic changes in urbanization and alterations in agricultural cover have considerable penalties for water demand. Analysis of GRACE data indicates a notable reduction in average TWS by 77.89 mm between 2002 and 2017, with an annual rate, estimated at −5.821 mm/year. Soil sampling in highly vulnerable areas confirms agricultural degradation attributed to elevated salinity levels, with EC values ranging from 3.60 to 190 ds/m. These finds provide valuable insights for stakeholders and policymakers, to make reliable strategies regarding water allocation, land use regulations, and climate change adaptation in the worldwide vulnerable deltas.